Eecoveky of cyclotrimethylene



Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE RECOVERY OF CYCLOTB-IMETHYLENE- TRINITRAMINE 'No Drawing. Application April 10, .1948, Serial No. 20,362

4 Claims. (.01. 260- 248) This invention relates in general to a process for the recovery of cyclotrimethylenetrinitramine, hereinafter referred to as cyclonite, from explosive mixtures and more particularly to a process for the recovery of cyclonite from mixtures with such substances as trinitrotoluene, tetryl, nitrocellulose, waxes, and various plasticizers.

cyclonite is a white crystalline substance with a melting point of about 202 to 204 0., depending on the method of manufacture, and is one of the most powerful of modern high explosives. While its primary use is in military explosive compositions, relatively small, but nevertheless substantial quantities of cyclonite are needed in the preparation of various smokeless powders and special industrial explosives. Since cyclonite is not being manufactured in quantity at the present time, the limited demand for cyclonite must be satisfied by its recovery from the surplus military explosives which contain it.

It is known to the art to separate cyclonite from explosive mixtures by dissolving the entire mixture in a common solvent such as acetone and then precipitating the various components from solution by agitating and adding water. This separation depends upon the difference in respective solubility of the components in the dilute solvent. This process has utility where it What not been necessary to obtain cyclonite of a high degree of purity. The process is unsatisfactory, however, when highly pure yields are desired without the necessity of subsequently refining the product. This is true because it is an inherent defect of such a process that small amounts of the components of the mixture, which separate either before or after the desired fraction, will be carried over with and contami nate the desired product. For example, if cyclonite and trinitrotoluene are dissolved in acetone and water is added, the cyclonite will precipitate in a mother liquor which is a concentrated solution of trinitrotoluene in acetone and water. The crystals will therefore contain substantial amounts of this mother liquid which washing will not remove. To purify it, it is therefore necessary to recrystallize until the necessary purity is achieved. This extra manipulation is undesirable from the standpoint of both economy and safety.

It has been found that the cyclonite contained in the available military explosive compositions has the desired particle size for use in propellant powder. ,It is therefore highly desirable to recover the cyclonite in such a manner that the particle size will be retained. This obviously cannot be done if the cyclonite is itself dissolved according to the prior art processes. When the cyclonite is so dissolved, it is exceedingly difficult to recrystallize to the desired particle size.

Now in accordance with the present invention it has been found that cyclonite may be recovered from explosive compositions in excellent yields, in a highly pure state, and in the desired particle size.

Generally described, the invention comprises the treatment of 'an explosive composition containing cyclonite with a solvent or mixture of solvents in which the cyclonite is substantially insoluble and the remaining components are soluble. Solvents such as chloroform, ethyl ether, mixtures of ethyl ether and ethyl alcohol, and mixtures of ethyl ether, ethyl alcohol and chloroform may be employed. Although acetone alone is an excellent solvent for cyclonite, it has been found that when acetone is mixed with the proper proportions of an aliphatic alcohol having from 2 to 4 carbon atoms, namely, ethyl, propyl, and isopropyl alcohols, very little cyclonite is dissolved and such mixtures are excellent solvents for the other ingredients of certain of the explosive mixtures containing cyclonite. However, of the above solvents and mixtures of solvents, a mixture of ethyl ether and ethyl alcohol has been found preferable.

The recovery process essentially comprises placing the explosive composition in a suitable vessel, adding the desired solvent or mixture of solvents, and agitating the mixture at temperatures which may vary from room temperature to the reflux temperature of the solvent. The cyclonite retains its crystalline form while the remaining components so into solution. Sen aration of the cyclonite from the solvent and dissolved materials may be achieved by filtration, centrifuging, Or other suitable procedure. The cyclonite is then washed; preferably with a small portion of solvent, which may be used in subsequent runs. The recovered cyclonite is now in a highly pure state and, if desired, may be removed directly from the filter and incorporated in the explosive or propellant for which it is required.

Having now generally disclosed the nature of the present invention, the following examples are given for purposes of illustration. Unless otherwise indicated, the specified amounts of explosive mixtures and solvent were placed in a vessel equipped with heating jacket, an agitator and a reflux condenser. Unless otherwise indicated, each charge was agitated at reflux temperature for 20 minutes. All parts are by vent and solvent amounts are shown in the folweight. lowing table:

Solvent Recovered Cyclonite Wt. Rinse Type Wt. Wt. Per cent Remarks 10D 95 36. 5 94. 8 White free-flowing. 175 100 36. 3 94. 3 Do. 300 100 36. 93. D0.

1 Agitated minutes instead of 20.

Example 1 Cyclonite was recovered from gram portions of an explosive mixture containing cyclonite and 40% TNT. Type and amount of solvent and results are shown in the table below:

Example 5 Cyclonite was recovered from 500 gram portions of an explosive containing about of cyclonite plasticized with a mixture of mono-, di-, and trinitrotoluenes; tetryl, nitrocellulose Solvent Recovered Cyclonite 't. Rinse Wt. Per cent Remarks chloroform 200 31. l 103. 7 Yellow cast.

Do. W. t 250 100 28. ii 95. 3 White, free-flowing. 1:2 ether/alcohol 200 100 37.0 123. 3

D0 A r 250 100 27. 2 90. 7 D0.

Example 2 and a solvent. The following table shows the Cyclonite was recovered from 50 gram portions of a plastic explosive containing about 88% solvent, the amounts of solvent used and the results obtained:

h l Wash Solvent Cyclonite Recovered Acetone \Vt. g Type Wt, g. Alcohol Acetone Wt. Per cent l Remarks 500 500 250 250 345 89 whitai'ree-flowing. 250 250 375 125 360 93 Do. 780 220 390 362 93 Do. 250 250 375 355 92 D0.

I Some cyclonite was lost due to slight solubility in the solvent mixture. However. yields can he improved by the recycling of the solvcnt. cyclonite mixed with petrolatum or other waxes. Type and amount of solvent and results are presented in the following table:

Example 6 A larger quantity of cyclonite was produced on plant scale by the following procedure: 18

Example 3 Cyclonite was recovered from 50 gram portions of an explosive containing about 80% of cyclonite which had been plasticized with a mixture of mono-, di-, and trinitrotoluenes; nitrocellulose and a solvent. The following table shows type and amount of solvent used and the results of the treatment:

pounds of the explosive treated in Example 4 were placed in a vessel equipped with an agita tor. Thirty-six pounds of a 2:1 mixture of ether-alcohol was added and the contents agitated for one-half hour at room temperature. The cyclonite was allowed to settle, the mother liquor was decanted, the cyclonite was washed with fresh solvent and filtered. All. of the wash Solvent Recovered cyclonite Wt. l

Rinse Type }Wt. Wt. Per cent Remarks I 1:2 Ether/Alon 250 100 39.2 96.8 White.

Do 200 100 40.4 100.0 Slighttint. 1:1 Ether/Ale 200 100 40.4 100.0 White, free-flowing.

Example 4 Cyclonite was recovered from an explosive containing about 75 of cyclonite plasticized with a mixture of mono-, di-, and trinitrotoluenes;

liquor and part of the mother liquor was recycled to form the extracting medium for the following batch. The yield from this process averaged about 98% of white, free-flowing crystetryl, nitrocellulose and. a solvent. Results, s0l-' 75 tals having a melting point of about 204.5 C.

and no nitro body odor. The following table shows the results of four typical runs:

Ether/Alcohol Wt. Rinse Recovered cyclonite Mother Wash mquor Liquor 2.1 E/Alc. Wt. Dry Per Cent M.P.,C.

19% 161-5; 18 13.54 96. 4 204. 5 21 l8 i3. 76 98. l 204. 5 15 21 18 13. 86 98. 7 204. 5 15 21 l8 13. 90 99. 0 204. 0

compositions vary and the solvent selected should be one which mo t readily dissolves the in redients to be removed. and which is substantially a nonsolvent for cyclonite.

The above examples clearly illustrate that hi hly pure cyclonite may be recovered from militarv explosive in good yields. The degree of purity may be readily controlled by the particular solvent, the amount of solvent. the agitation time, and the temperatures employed. The highe t possible purity is of course attained when all of the components other than the cyclonite are completely dissolved leaving the cyclonite crystals in t e same condition as when they were incorporated in the mixture under treatment. If this is not done, the crystals will be externallv contaminated to a relative degree and will be charact rized by discoloration, odor, difference in rneltins points, etc.

It is generally preferred to carry out the extraction proce s at the reflux tem erature of the solvent employed because less solvent is reouired at that temperature than at lower temperatures. Ho ever, a comparison of Examples 4 and 6 illustrates that by recvcling the wa h liquor and a po tion of the mot er li uor, hi h purity and efficiency can still be achieved at room temperatures without too great an increase in solvent cost and extraction time.

The vessel employed may be of any suitable type equip ed with a itating means, a heat ng means, and a reflux condenser. Since all of the preferred solvents boil substantially below 100 C., adequate heating can be accomplished by employing a jacketed vessel and circulating water through the Jacket at the desired temperature.

The components of the ex losive mixtures other than the cyclonite may be recovered or disposed of as circumstances warrant. The u ed solvents may be mixed with water and recovered for re-use by rectification.

What I claim and desire to protect by Letters Patent is:

1. A process for the recovery of cyclonite crystals from explosive mixtures containing cyclonite crystals and at least one of the group consisting of mononitrotoluene, dinitrotoluene, trinitrotoluene, nitrocellulose, and tetryl which comprises mixing together the explosive mixture and a member of the group of solvent mixtures consisting of a mixture of ethyl ether and ethyl alcohol, a mixtur of ethyl ether, ethyl alcohol, and chloroform, and a mixture of acetone with an aliphatic alcohol having from 2 to 4 carbon atoms; agitating the mixture of explosive and solvent at a temperature of from room temperature to the reflux temperature of th solvent until substantially all of the explosive mixture except the cyclonite crystals is in solution; and separating the cyclonite crystals from the solution.

2. A process for the recovery of cyclonite crys- 5 tals from explosive mixtures containing cyclonite crystals and at least one of the group consisting of mononitrotoluene, dinitrotoluene, trinitrotoluene, nitro ellulose, and tetryl which comprises mixing to ether the explosive mixture and a solvent mixt re of ethyl ether and ethyl alcohol; agitating the mixture of explosive and the solvent mixture at a temperature of from room temperature to the reflux tempe ature of the solvent until substantiallv all of the ex losive mixture exce t the cyclonite crystals is in solution; and se arating the cyclonite crystals from the solution.

3. A process for the recovery of cyclonite crystals from explosive mixtures containing cyclonite crystals and at least one of the group consisting of mononitrotolvene, dinitrotoluene, trinitrotoluene, nitrocellu ose, and tetryl which comprises mixing together the explosive mixture and a solve t mixture of ethyl ether, ethyl alcohol and chloroform; agitating the mixture of explosive and the so vent mixture at a temperature of from room te perature to the reflux temper ture of the solvent until substantially all of t e explosive mixture except the cyclonite crystals is in solution: and separating the cyclonite crystals from t e solution.

4. A process for the recovery of cyclonite crystals from ex losive mixtures containing c clonite cr sta s and at least one of the group consisting of mononitrotol ene, dinitrotoluene, trinitrotoluene, nitrocellulose, and tetryl which comprises mixing toget er the explosive mixture and a solve t mixture of acetone with an aliphatic alcohol havi g from 2 to 4 carbon ato s; agitating the mixt re of explosive and the solvent mixture at a temperature of from room temperature to the reflux tempeuzture of the solvent until substantially all of the explosive mixture except the cyclonite crystals is in solution: and separating the cyclonite cryst l rom t e sol t o WILLARD DE C. CRA'IER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1.402 693 Herz Jan. 3, 1922 2.355,770 Wyler Aug. 15, 1944 2,410,669 Wyler Nov. 5, 1946 2,398,080 Caesar Apr. 9, 1946 2,418,753 Burtle Apr. 8, 1947 2,439,648 Burtle Apr. 13, 1948 OTHER REFERENCES Chemie et Industrie, vol. 28, No. 15, Nov., 1932, pp. 1038-1044. 

1. A PROCESS FOR THE RECOVERY OF CYCLONITE CRYSTALS FROM EXPLOSIVE MIXTURES CONTAINING CYCLONITE CRYSTALS AND AT LEAST ONE OF THE GROUP CONSISTING OF MONONITROTOLUENE, DINTROTOLUENE, TRINITROTOLUENE, NITROCELLULOSE, AND TETRYL WHICH COMPRISES MIXING TOGETHER THE EXPLOSIVE MIXTURE AND A MEMBER OF THE GROUP OF SOLVENT MIXTURES CONSISTING OF A MIXTURE OF ETHYL ETHER AND ETHYL ALCOHOL, AMIXTURE OF ETHYL ETHER, ETHYL ALCOHOL, AND CHLOROFORM, AND A MIXTURE OF ACETONE WITH AN ALIPHATIC ALCOHOL HAVING FROM 2 TO 4 CARBON ATOMS: AGITATING THE MIXTURE OF EXPLOSIVE AND SOLVENT AT A TEMPERATURE OF FROM ROOM TEMPERATURE TO THE REFLUX TEMPERATURE OF THE SOLVENT UNTIL SUBSTANTIALLY ALL OF THE EXPLOSIVE MIXTURES EXCEPT THE CYCLONITE CRYSTALS IS IN SOLUTION; AND SEPARATING THE CYCLONITE CRYSTALS FROM THE SOLUTION. 